1. Field of the Invention
The present invention relates to a linear actuator in which a slider reciprocates in the axial direction of a main cylinder body by introducing a pressure fluid from a fluid inlet/outlet port, and a method for processing the linear actuator to provide rolling grooves for the slider.
2. Description of the Related Art
A linear actuator has been hitherto used as a means for transporting a workpiece or the like. Such a linear actuator transports a workpiece placed on a slide table by allowing the slide table to perform the linear reciprocating motion along a main cylinder body.
The present applicant has proposed a linear actuator comprising a main cylinder body in which a piston is accommodated displaceably therein, a rod which is connected to the piston and which protrudes from the main cylinder body to the outside, and a slide table which includes an end plate connected to an end of the rod and a table connected to the end plate (see Japanese Laid-Open Patent Publication No. 9-141533). In this linear actuator, the slide table is provided displaceably in the axial direction of the main cylinder body. A pair of guide blocks are formed in an expanded manner on the upper surface of the main cylinder body.
In the linear actuator, a guide section of the slide table is inserted into the space between the pair of guide blocks. Ball grooves, on which balls roll, are formed on the guide section and the side surfaces of the guide blocks opposed thereto respectively. When air is supplied to a port of the main cylinder body, the piston is moved, and the slide table, which is attached to the upper surface of the main cylinder body, is moved integrally under the cooperative action of the balls and the guide blocks.
The present applicant has further proposed a linear actuator in which a plurality of columnar roller bearings are provided, and rolling grooves of a slider and guide rails for allowing the roller bearings to roll are provided (see Japanese Laid-Open Patent Publication No. 7-110011). Each of the rolling grooves is formed to have a substantially V-shaped cross section. The roller bearings and rolling grooves are provided in place of the balls and the ball grooves in the linear actuator of Japanese Laid-Open Patent Publication No. 9-141533 described above. In this linear actuator, the plurality of roller bearings are inclined alternately by 90° along the rolling grooves. When the slide table is displaced along the main cylinder body, the roller bearings roll along the rolling grooves.
In general, in the case of the linear actuators as described above, additional processing is applied to the ball grooves and the rolling grooves when the slide table is formed. Accordingly, accuracy is improved for the ball grooves and the rolling grooves to reduce the sliding resistance brought about when the balls and the roller bearings roll. The processing is performed, for example, such that a rotating polishing jig is moved along the ball groove and the rolling groove in a state in which the rotating polishing jig abuts against the ball groove and the rolling groove.
In relation to the conventional techniques as described above, there is a demand to integrally form the end plate and the table of the slide table in order to reduce the number of parts of the linear actuator and the number of steps of assembling the linear actuator.